Process for hydroxylating triorganosiloxylated siloxanes



United States Patent Ofifice 3,394,321 Patented Feb. 14, 1967 This invention relates to a process for hydroxylating triorganosiloxylated siloxanes. More specifically, this invention relates to a process for replacing trialkylsiloxy or trihaloalkylsi-loxy'groups in siloxanes with hydroxyl groups.

It has been found in accordance with this invention that when a triorganosiloxylated siloxane is reacted with a cataylst selected from the group consisting of aluminum chloride, titanium tetrachloride and sulfuric acid and then the product of this reaction is hydroylzed, a product is obtained in which one or any number of the triorganosiloxy groups of the siloxane have been replaced by hydroxyl groups.

The process of this invention is particularly useful for hydroxylating completely trimethylsiloxylated siloxanes. The process of this invention is also useful in analyzing the number of trimethylsiloxy groups put on the surface of fillers when they are treated. Other uses of the process of this invention will be obvious to those skilled in the art from the foregoing description of the invention .as well as from the following, more detailed, description and ex amples.

The temperature .at which the process of this invention is carried out is not particularly critical. Generally speaking, the reaction is carried out at about room temperature or below, that is, at a temperature 'below about 30 C. It is usually preferable to carry out the reaction at a temperature below about C. because the reaction tends to be exothermic and also because the lower temperature tends to prevent condensation of the silicon-bonded hydroxyl groups produced during the reaction.

The relative amounts of the catalyst and siloxane employed can vary over a considerable range. Thus, for example, the amount of catalyst employed can range from less than an equimolar amount to several times an equimolar amount. However, it is generally preferable to employ one mole of catalyst per mole of SiO structure (i.e., per mole of unsubstituted silicon) in the siloxane since this ratio appears to give the best overall results.

The reaction time basicallyetfects the yield obtained. otherwise, there is no particualrly critical reaction time involved. Satisfactory results can be obtained in either relatively short times, say 30 minutes or less, orin relatively long times, say-a few days.

In hydrolyzing the reaction. product a cold aqueous HCl solution is generally employed. The HCl is not essential tothe hydrolysis but is merely employed to prevent precipitation of any salts that may be formed. Hydrolysis can also be accomplished by pouring the reaction product onto ice or' into an ice-water mixture. v As a matter of convenience and for ease of handling, the process of this invention is preferably carried out in a suitable solvent. However, when the starting siloxane is a liquid, the use of a solvent is not essential although still helpful.

The triorganosiloxylated siloxanes that can be hydroxylated employing the process of this invention include any siloxane containing R SiO-groups wherein each R is a radical independently selected from the group consisting of alkyl and haloalkyl radicals. Of course, the R SiO- groups are attached to the siloxane via Si-O-Si bonds.

The R radicals can be any .alkyl or haloalkyl radicals. Illustrative of the alkyl and haloalkyl radicals represented by -R are the methyl, ethyl, propyl, isopropyl, butyl, tertiary butyl, amyl, hexyl, oetyl, decyl, dodecyl, octadecyl, myricyl, chloromethyl, 3,3,3-trifluoropropyl, chloroisobutyl and the 3-bromopropyl radicals.

Siloxanes that are particularly useful in the process of this invention are those which are completely triorganosiloxylated, the completely trimethylsiloxylated siloxanes being the most preferred compounds. These compounds can be represented by the respective formulae es n RaSi OS i l 32-] wherein R 'has the above defined meaning and n is an integer.

For purposes of illustration, the reactions that take and OSi(CHs)a In order that those skilled in the art can better understand how the present invention can be practiced, the

following examples are given by way of illustration and not by way of limitation.

Example 1 This example shows the effect of varying the amount of catalyst (aluminum chloride) used and the reaction times.

Five runs were made using the following procedure. A mixture of 10 ml. (.0225 mol) of [(CH SiO] Si and 10 ml. of toluene was placed in a 1 ounce glass vial and cooled to l() to 15 C. Then the desired weight of aluminum chloride was added, the vial capped and the mixture shaken for 2 minutes, and then the ,mixture was allowed to stand. The mixture was then hydrolyzed by pouring it into 30 ml. of cold 10 percent HCl, shaken for 30 seconds, separated, then washed twice more with 10 percent HCl, then washed twice with water, then contacted with calcium'oxide for one minute and finally filtered. The filtered product was then analyzed by gas-.

liquid chromatographic analysis to determine the ratio of [(CH SiO] SiOH to [(CH SiO] Si. The amounts of aluminum chloride, the reaction times and the results are set forth in the table below.

added to one liter of 10 percent HCl over a period of about 10 minutes, a maximum temperature of 10 C. being reached during the additionto the HCl. The solution was then Washed two more times with cold 10 percent HCl minutes each) and then twice with water. Finally the mixture was treated with CaO and then filtered throughfilter aid.

The above procedure was repeated and then. the two toluene solutions obtained were combined. The toluene solution was azeotroped yielding 4 tov 5 m1. of water and then stripped to remove the toluene. The remaining liquid was filtered and then fractionated into four cuts of 100 ml., 50 ml., 50 ml. and 15 ml. By gas-liquid chromatographic analysis they contained 78 percent, 72 percent, 55 percent and 51 perccnt,.respectively, of

The four cuts were combined for refractionation. 135 g. (about 100 cc.) of [(CH) SiO] SiOSi(OH) [OSi(CH was obtained at a temperature of 8889 C. and about .15 mm. of pressure.

showed. that 3.2 percent of [(CH l SiO] SiOHhad been a Example 4 f f g f fggg Reaction Time 100 ml. of toluene, 100 ml. (.225 mol) of CH SiO] .,Si

3 e 32 {25 5 and 12.25 ml. (.112 mol) of titanium tetrachloride were placed in a 500 ml. flask and allowed to react for 46.5 11 hours 13 1133 55551111 hours at room temperature. The mixture was then hydrolyzed with a. percent HCl solution, washed twice Example 2 with water?, drizcll, and t lhgn anallyz edhby gills-lliquitli1 chro- 10 ma ograp 10 an ysls. e ana ysis s owe t att e pro- This example also. shows the effect of varying the d t t d 113 t amount of catalyst (aluminum chloride) used. uc con ame pawn of [(CH3)3S10]3S10H' Five. runs were made using the following procedure. Example 5 A mlxture of (0224 inole) of This example shows the effect of time on the reaction.

J [OSKCHaMEl 15 j I [OSKOHSMzl (cmasiTos I OSKCHH 68g.(.112rnol)oi (onmsi l 0Si--TOSi(OHa)s 2 and 10 ml. of toluene was placed in a small bottle and 50 ml. of toluene and m1 169 mol) of titanium cooled 9 about Then the appropgate quapmy tetrachloride were mixed at room temperature. Periodiof aluminum chloride was added and the mixture stirred cany a Sample of the mixture was removed hydrolyzed g i a iz f g fg igmperature fi ngamltamed with a 10 percent HCl solution, washed, filtered and then e P? i was analyzed by gas-liquid chromatographic analysis to deg an S a i i 2 g a m iii termine the amount of starting siloxane converted to hy e mlxture was en 3 r0 yz y pouring H mm droxylated product. The results are set forth in the table ml. of cold 10 percent HCl, shaken, separated, then below washed twice more with 10 percent HCl, then washed twice with water, filtered, weighed and then analyzed by [OSi(CHs)a]2 gas-liquid chromatographic analysis. The amounts of (CHmsi Osi 1 OH aluminum chloride andthe results are set forth in the I table below.

i TABLE Mole Ratio A161; to Percent Yield as Percent Yield as [OSi(C-Ha)a]2l [OSKCHzOflzl [OSKCHahhl (CH3)3Si-OSi0Si(CHs)3 HOSi-OH (oHmSi osi---0H' l I 1 l I, l l

Example 3 Reaction time: p I 465 g. of hexakis(trimethylsiloxy)disiloxane, g f gf igi Z3; Qa h h 3 hours, percent 75 was dissolved in 500 ml. of toluene, placed in a three 23 hoursrpercent 74' liter flask and cooled to 2. C. Then 112 g. of AlCl was added over a period of about 7 minutes, a maximum Example 6 temperature of 9 C. being reached during the addition. The mixture was stirred an additional 5 minutes and then 10 1 (.225 ol) of [(CH SiO] Si'were' mixed with 10 ml. of toluene in a bottle and cooled to -10 C.

Then 0.7 ml. (.0169 mol) of 97 percent sulfuric acid was added to the bottle. The mixture was shaken intermittently for one hour, the temperature beingmaintained at formed.

Example 7 When the siloxanes specified below arev substituted for equimolar amounts, the indicated products are obtained.

Siloxane 1) zH5)sSi Product 1 6. The process of claim 5 wherein the catalyst is aluminum chloride.

7. The process of claim 5 wherein the catalyst is titanium tetrachloride. 5 8. The process of claim 5 wherein the catalyst is sulfuric acid.

9. A process for hydroxylating triorganosiloxylated siloxanes which comprises the steps of (1) reacting a triorganosiloxylated siloxane having the general formula 10 Product (2) I [0S a)2( 2Hs)]2l (OSiRa)z"| (CH3)z(C3H5)Si-O$i 0H RaSiTOSi OSiRa i, Siloxane (3) J [OSi(CH3)2(CHzCH2CF3 ]2l 0 mcmcm c11 si-osi--0 a)2( 2 Product (3) wherein each R is a radical independently selected from the group conslsting of the methyl, ethyl and I [OSi(CHa)2( zCH2C F9121 3,3,3-trifluoropropyl radicals and n is an integer, with 0H a catalyst selectedfrorn the group consisting of alu- 1 L minum chloride, titanium tetrachloride and sulfuric acid, (2) hydrolyzing the reaction product and Siloxane (4) Product (4) [O- Si(C 1 11393121 raHa1)a That which is claimed is: 1. A process for hydroxylating triorganosiloxylated siloxanes which comprises the steps of (1) reacting a triorganosiloxylated siloxane with a catalyst selected from the group consisting of aluminum chloride, titanium tetrachloride and sulfuric acid, (2) hydrolyzing the reaction product and (3) recovering the hydroxylated product. 2. The process of claim 1 wherein the catalyst is aluminum chloride.

3. The process of claim 1 wherein the catalyst is titanium tetrachloride.

4. The process of claim 1 wherein the catalyst is sulfuric acid.

5. A process for hydroxylating triorganosiloxylated siloxanes which comprises the steps of (l) reacting a triorganosiloxylated siloxane having the general formula R Si osin,

wherein each R is a radical independently selected from the group consisting of alkyl and haloalkyl radicals and n is an integer, with a catalyst selected from the group consisting of aluminum chloride, titanium tetrachloride and sulfuric acid,

(2) hydrolyzing the reaction product and (3) recovering the hydroxylated product.

(3) recovering the hydroxylated product.

10. The process of claim 9 wherein the catalyst is aluminum chloride.

11. The process of claim 9 wherein the catalyst is titanium tetrachloride.

12. The process of claim 9 wherein the catalyst is sulfuric acid.

13. A process for hydroxylating triorganosiloxylated siloxanes which comprises the steps of tetrachloride and sulfuric acid, (2) hydrolyzing the reaction product and (3) recovering the hydroxylated product. 14. The process of claim 13 wherein the catalyst is aluminum chloride.

15. The process of claim 13 wherein the catalyst is titanium tetrachloride.

16. The process of claim 13 wherein the catalyst is sulfuric acid. 17. A process for hydroxylating the siloxane s sSiO] i which comprises the steps of 1) reacting the siloxane with a catalyst selected from the group consisting of aluminum chloride, titanium tetrachloride and sulfuric acid, (2) hydrolyzing the reaction product and (3) recovering the hydroxylated product [(CH SiO] SiOH 18. The process of claim 17 which is carried out at room temperature or below.

3, 304,3 2 1 7 8 19. A, process for hydroxylatin g the siloxane (3) recovering the hydroxylated product I [OSi(C Hskhl J [CRSKCHahhl OSiOSi(CH3)3 (GH3)aSi--OSi l. L 5 l L which comprises the steps of (1) reacting the siloxane with a catalyst selected from the group consisting of aluminum chloride, titanium tetrachloride and sulfuric acid, (2) hydrolyzing the reaction product and 10 P. F. SHAVER, Assistant Examiner.

No references cited.

HELEN MCCARTHY, Acting Primary Examiner. 

1. A PROCESS FOR HYDROXYLATING TRIORGANOSILOXYLATED SILOXANES WHICH COMPRISES THE STEPS OF (1) REACTING A TRIORGANOSILOXYLATED SILOXANE WITH A CATALYST SELECTED FROM THE GROUP CONSISTING OF ALUMINUM CHLORIDE, TITANIUM TETRACHLORIDE AND SULFURIC ACID, (2) HYDROLYZING THE REACTION PRODUCT AND (3) RECOVERING THE HYDROXYLATED PRODUCT.
 9. A PROCESS FOR HYDROXYLATING TRIORGANOSILOXYLATED SILOXANES WHICH COMPRISES THE STEPS OF (1) REACTING A TRIORGANOSILOXYLATED SILOXANE HAVING THE GENERAL FORMULA 